We are running a site with quite good traffic (http://www.anses.gob.ar, 8MM users/month) and we are extremely happy with Middleman.

Webpack 2 is our external pipeline and we setup asset hashing (the middleman one). We have a few background images in our css, and I don't know how to properly call the images in css so that the asset hashing works in our case. I do understand the disconnection about web pack and asset hashing, but Im unable to fix it